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87-424: Time Wars may refer to: Time War ( Doctor Who ) , a conflict mentioned in the television series Doctor Who TimeWars , a series of science fiction novels by Simon Hawke Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Time Wars . If an internal link led you here, you may wish to change

174-586: A Time Rift in Cardiff . The Time War provides a convenient in-story explanation for any contradictions in series continuity: for example, writer Paul Cornell has suggested that Earth's destruction by an expanding sun in "The End of the World" five billion years hence, as opposed to the original depiction of its demise around the year 10,000,000 AD in The Ark (1966), can be attributed to changes in history due to

261-652: A story arc stretching through several of the Eighth Doctor Adventures novels, the Doctor learns that, at some point in his personal future, a war will be fought between the Time Lords and an unnamed enemy. Russell T Davies commented that there is no connection between the war of the books and the Time War of the television series, comparing the wars with Earth's two World Wars. He also said that he

348-451: A . The pulse is reflected from a mirror situated a distance a from the light source (event Q), and returns to the light source at x ′ = 0,  ct ′ =  a (event R). The same events P, Q, R are plotted in Fig. 2-3b in the frame of observer O. The light paths have slopes = 1 and −1, so that △PQR forms a right triangle with PQ and QR both at 45 degrees to

435-705: A cache of forbidden doomsday weapons known as the Omega Arsenal, save one: "the Moment". Moreover, they resurrect the Master , a renegade Time Lord and nemesis to the Doctor, as they believe him to be the "perfect warrior for a time war". However, after the Dalek Emperor gained control of the Cruciform, the Master deserted his post. Leadership among the Time Lords remained vague during the earlier phase of

522-445: A fourth dimension, it is treated differently than the spatial dimensions. Minkowski space hence differs in important respects from four-dimensional Euclidean space . The fundamental reason for merging space and time into spacetime is that space and time are separately not invariant, which is to say that, under the proper conditions, different observers will disagree on the length of time between two events (because of time dilation ) or

609-420: A geometric interpretation of special relativity that fused time and the three spatial dimensions into a single four-dimensional continuum now known as Minkowski space . This interpretation proved vital to the general theory of relativity , wherein spacetime is curved by mass and energy . Non-relativistic classical mechanics treats time as a universal quantity of measurement that is uniform throughout,

696-453: A great shock when Einstein published his paper in which the equivalence of the different local times of observers moving relative to each other was pronounced; for he had reached the same conclusions independently but did not publish them because he wished first to work out the mathematical structure in all its splendor. He never made a priority claim and always gave Einstein his full share in the great discovery. Minkowski had been concerned with

783-574: A light signal in that same time interval Δ t {\displaystyle \Delta t} . If the event separation is due to a light signal, then this difference vanishes and Δ s = 0 {\displaystyle \Delta s=0} . When the event considered is infinitesimally close to each other, then we may write In a different inertial frame, say with coordinates ( t ′ , x ′ , y ′ , z ′ ) {\displaystyle (t',x',y',z')} ,

870-434: A location. In Fig. 1-1, imagine that the frame under consideration is equipped with a dense lattice of clocks, synchronized within this reference frame, that extends indefinitely throughout the three dimensions of space. Any specific location within the lattice is not important. The latticework of clocks is used to determine the time and position of events taking place within the whole frame. The term observer refers to

957-542: A means for his timeline to correct itself, leaving the Doctor with the belief he had in fact used the Moment to destroy Gallifrey, the Time Lords, and the Daleks. The Doctor is haunted with the false knowledge of his home planet's demise, with even some of his enemies using that guilt against him. Throughout series 5 , the Eleventh Doctor encounters cracks in "the skin of the universe". The Doctor learns that

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1044-442: A mere shadow, and only some sort of union of the two shall preserve independence." Space and Time included the first public presentation of spacetime diagrams (Fig. 1-4), and included a remarkable demonstration that the concept of the invariant interval ( discussed below ), along with the empirical observation that the speed of light is finite, allows derivation of the entirety of special relativity. The spacetime concept and

1131-571: A mission with the Derek Jacobi Master, and the resurrection of Rassilon through a complex Time Lord project that allowed Rassilon's consciousness to take over the body of another Time Lord. The Dark Eyes audio series is also in effect a lead up to the Last Great Time War from the Doctor's perspective, the first series being a complex plan by the Daleks to erase the Time Lords from existence. Dark Eyes 2 also sees

1218-523: A non-corporeal collective consciousness that would be the only sentient form of life in existence. The Time Lords, apparently hardened by the horrors of war, give near-unanimous support for this plan – only two Time Lords dissented when the issue is put to a full vote. While the High Council continues to lead Time Lord society during the war, a separate War Council is tasked with overseeing the war itself, as well as Gallifrey's defences. The War Council

1305-419: A person moving with respect to the first observer will see the two events occurring at different places, because the moving point of view sees itself as stationary, and the position of the event as receding or approaching. Thus, a different measure must be used to measure the effective "distance" between two events. In four-dimensional spacetime, the analog to distance is the interval. Although time comes in as

1392-413: A single point in spacetime. Although it is possible to be in motion relative to the popping of a firecracker or a spark, it is not possible for an observer to be in motion relative to an event. The path of a particle through spacetime can be considered to be a sequence of events. The series of events can be linked together to form a curve that represents the particle's progress through spacetime. That path

1479-433: A spacetime diagram illustrating the world lines (i.e. paths in spacetime) of two photons, A and B, originating from the same event and going in opposite directions. In addition, C illustrates the world line of a slower-than-light-speed object. The vertical time coordinate is scaled by c {\displaystyle c} so that it has the same units (meters) as the horizontal space coordinate. Since photons travel at

1566-490: A spatial distance Δ x . {\displaystyle \Delta x.} Then the squared spacetime interval ( Δ s ) 2 {\displaystyle (\Delta {s})^{2}} between the two events that are separated by a distance Δ x {\displaystyle \Delta {x}} in space and by Δ c t = c Δ t {\displaystyle \Delta {ct}=c\Delta t} in

1653-531: A woman from a spaceship crashing towards the planet Karn fails, when she refuses his aid because he is a Time Lord, apparently believing that the Time Lords had become just as destructive as the Daleks. The Doctor is killed in the crash, but is temporarily restored to life by the Sisterhood of Karn, who finally convince him to fight for the sake of the universe. They further offer an elixir that would control his regeneration. The Doctor accepts, remarking that there

1740-643: A year before his death), Minkowski introduced his geometric interpretation of spacetime in a lecture to the Göttingen Mathematical society with the title, The Relativity Principle ( Das Relativitätsprinzip ). On 21 September 1908, Minkowski presented his talk, Space and Time ( Raum und Zeit ), to the German Society of Scientists and Physicians. The opening words of Space and Time include Minkowski's statement that "Henceforth, space for itself, and time for itself shall completely reduce to

1827-408: Is "invariant". In special relativity, however, the distance between two points is no longer the same if measured by two different observers, when one of the observers is moving, because of Lorentz contraction . The situation is even more complicated if the two points are separated in time as well as in space. For example, if one observer sees two events occur at the same place, but at different times,

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1914-415: Is a measure of separation between events A and B that are time separated and in addition space separated either because there are two separate objects undergoing events, or because a single object in space is moving inertially between its events. The separation interval is the difference between the square of the spatial distance separating event B from event A and the square of the spatial distance traveled by

2001-419: Is actually what is indicated by moving clocks by applying an explicitly operational definition of clock synchronization assuming constant light speed. In 1900 and 1904, he suggested the inherent undetectability of the aether by emphasizing the validity of what he called the principle of relativity . In 1905/1906 he mathematically perfected Lorentz's theory of electrons in order to bring it into accordance with

2088-408: Is called an event , and requires four numbers to be specified: the three-dimensional location in space, plus the position in time (Fig. 1). An event is represented by a set of coordinates x , y , z and t . Spacetime is thus four-dimensional . Unlike the analogies used in popular writings to explain events, such as firecrackers or sparks, mathematical events have zero duration and represent

2175-550: Is called the particle's world line . Mathematically, spacetime is a manifold , which is to say, it appears locally "flat" near each point in the same way that, at small enough scales, the surface of a globe appears to be flat. A scale factor, c {\displaystyle c} (conventionally called the speed-of-light ) relates distances measured in space to distances measured in time. The magnitude of this scale factor (nearly 300,000 kilometres or 190,000 miles in space being equivalent to one second in time), along with

2262-466: Is led by an unknown Time Lord general. During the last days of the Time War, the War Council apparently becomes disillusioned with the High Council. On the last day of the Time War, the Daleks launched what is said to be their biggest attack ever on Gallifrey. Dalek forces captured the city of Arcadia, then laid siege to the capital itself. The War Doctor stole an ancient Gallifreyan weapon known as

2349-568: Is no preferred origin, single coordinate values have no essential meaning. The equation above is similar to the Pythagorean theorem, except with a minus sign between the ( c t ) 2 {\displaystyle (ct)^{2}} and the x 2 {\displaystyle x^{2}} terms. The spacetime interval is the quantity s 2 , {\displaystyle s^{2},} not s {\displaystyle s} itself. The reason

2436-514: Is positive, the spacetime interval is referred to as timelike . Since spatial distance traversed by any massive object is always less than distance traveled by the light for the same time interval, positive intervals are always timelike. If s 2 {\displaystyle s^{2}} is negative, the spacetime interval is said to be spacelike . Spacetime intervals are equal to zero when x = ± c t . {\displaystyle x=\pm ct.} In other words,

2523-444: Is revealed to be the Master . The Master had been hiding in human form at the end of the universe using a Chameleon Arch , having escaped the destruction of both the Time Lords and the Daleks. By taking human form, he avoided detection by the Doctor, who was apparently unaware of his nemesis' resurrection during the Time War. The Master had remained ignorant of the latter phase and outcome of the war until he emerged from hiding, when he

2610-412: Is separate from space, and is agreed on by all observers. Classical mechanics assumes that time has a constant rate of passage, independent of the observer's state of motion , or anything external. It assumes that space is Euclidean : it assumes that space follows the geometry of common sense. In the context of special relativity , time cannot be separated from the three dimensions of space, because

2697-599: Is that unlike distances in Euclidean geometry, intervals in Minkowski spacetime can be negative. Rather than deal with square roots of negative numbers, physicists customarily regard s 2 {\displaystyle s^{2}} as a distinct symbol in itself, rather than the square of something. In general s 2 {\displaystyle s^{2}} can assume any real number value. If s 2 {\displaystyle s^{2}}

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2784-635: Is told by the Doctor many years later. The timelines of other races and planets shift without the inhabitants of the worlds affected being aware of the changes in history , as they were a part of them. Most affected were the Zygons , who lost their home planet, Zygor, and attempted to conquer Earth for its resources; the Eternals , and the Gelth , who lost their physical form and were reduced to gaseous beings, who attempted to possess human corpses in 1869 using

2871-434: Is used by both sides to reverse battles that caused massive fatalities on both sides. These excesses of temporal warfare eventually leads to the whole of the conflict becoming "time-locked", so that no time traveller could go back into it. The Doctor describes the final days of the war as "hell". As the war progresses, the Time Lords become increasingly aggressive and unscrupulous. Growing in desperation, they access and use

2958-564: Is used to create a link between the final day of the Time War and Earth so the Master could release Gallifrey from the Time Lock. The plan ultimately fails, as the Doctor destroyed the diamond link and the Master apparently sacrificed his life to take revenge on Rassilon, sending the Time Lords back to their apparent doom. However, as "the Moment" had a will of its own, it showed the War Doctor an alternative solution and ultimately enabled

3045-400: The c t {\displaystyle ct} -coordinate is: or for three space dimensions, The constant c , {\displaystyle c,} the speed of light, converts time t {\displaystyle t} units (like seconds) into space units (like meters). The squared interval Δ s 2 {\displaystyle \Delta s^{2}}

3132-461: The distance Δ d {\displaystyle \Delta {d}} between two points can be defined using the Pythagorean theorem : Although two viewers may measure the x , y , and z position of the two points using different coordinate systems, the distance between the points will be the same for both, assuming that they are measuring using the same units. The distance

3219-465: The Eighth Doctor and set during the early years of the Time War. With the announcement of The War Doctor , Big Finish Productions also announced a prequel box set featuring the Eighth Doctor during the early days of the conflict, later expanded into a four-volume series. Paul McGann reprised his role with Rakhee Thakrar playing Bliss, his new companion. The third volume also features

3306-642: The Time Lords of Gallifrey against the Daleks of Skaro . The specific incident that sparked the conflict remains unclear, but according to executive producer Russell T Davies , the origins dated back to conflicts between the Doctor and the Daleks. In Genesis of the Daleks (1975), the Time Lords—having foreseen the possibility of the Daleks conquering the universe—send the Fourth Doctor into

3393-429: The ct ′ axis is tilted with respect to the ct axis by an angle θ given by The x ′ axis is also tilted with respect to the x axis. To determine the angle of this tilt, we recall that the slope of the world line of a light pulse is always ±1. Fig. 2-3c presents a spacetime diagram from the viewpoint of observer O′. Event P represents the emission of a light pulse at x ′ = 0, ct ′ = −

3480-587: The data reduction following an experiment, the time when a signal is received will be corrected to reflect its actual time were it to have been recorded by an idealized lattice of clocks. In many books on special relativity, especially older ones, the word "observer" is used in the more ordinary sense of the word. It is usually clear from context which meaning has been adopted. Physicists distinguish between what one measures or observes , after one has factored out signal propagation delays, versus what one visually sees without such corrections. Failing to understand

3567-660: The Dalek Emperors in Remembrance of the Daleks (1988). The Time War officially began with the extinction of several time-traveling powers allied with the Time Lords known as the Temporal Powers. With the Temporal Powers being wiped out one-by-one, the Time Lords formally declared war with the Daleks. The 'duration' and extent of the War has been unclear, with the Daleks vanishing out of time and space to fight

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3654-520: The Dalek plot involving the destruction of the rift and all inhabited planets around it. The Doctor sabotages Rassilon's plan and uses the energy of the rift to erase the Daleks' scheme, but the actions of a Time Lord agent result in Cinder's death, leaving the War Doctor resolved to end the war once and for all as he recognises how far his people have fallen in the name of victory. The War Doctor series

3741-414: The Daleks trick the Eleventh Doctor into activating a Progenitor device which creates a new "Paradigm" of Daleks that destroy the previous Daleks and escap through time, forming a new race of Daleks. After the Time War, the Doctor is convinced that he is the only surviving Time Lord, saying that he would know of any others if they had survived. The Doctor later encounters a man named Professor Yana who

3828-405: The Doctor explains that, when the Time Lords were around, travel between parallel universes is less difficult but, with their demise, the paths between worlds are now closed. The Time Lords could also prevent or repair paradoxes such as the one created by Rose in an attempt to save her father's life in a traffic accident. Dalek survivors of the war appeared regularly across many episodes, until

3915-464: The Last Great Time War , is a conflict within the fictional universe of the British science fiction television series Doctor Who . The war occurs between the events of the 1996 film and the 2005 revived series , with the Time Lords fighting the Daleks until the apparent mutual destruction of both races. The war was frequently mentioned when the show returned, but was not directly seen until

4002-585: The Lorentz group are closely connected to certain types of sphere , hyperbolic , or conformal geometries and their transformation groups already developed in the 19th century, in which invariant intervals analogous to the spacetime interval are used. Einstein, for his part, was initially dismissive of Minkowski's geometric interpretation of special relativity, regarding it as überflüssige Gelehrsamkeit (superfluous learnedness). However, in order to complete his search for general relativity that started in 1907,

4089-407: The Moment, and intended to reduce Gallifrey into "rocks and dust" with the inferno wiping out the Dalek fleet. Rassilon and his fellow councillors attempt to escape the Time Lock by retroactively planting a four-note drumbeat into the Master's brain as a child and cause his descent into madness. From there, once the signal is made tangible enough, a Whitepoint Star, a diamond only found on Gallifrey,

4176-680: The Time Lords it is safe for them to return to the universe. Fleets of various races, some being former War participants, gathered in Trenzalore's orbit to either prevent the Doctor from speaking his name, or resume the War if the Time Lords return. The Church of the Papal Mainframe undergoes a faith change into the Church of the Silence as a dedication to keeping the peace, with a rogue chapter led by Madame Kovarian unknowingly causing

4263-466: The War, would indicate that it is not waged in normal space-time . Nonetheless, there was fighting in a sufficient bulk of the cosmos, including on the planet Gallifrey. The Doctor claims to have fought on the front lines and was present at the Fall of Arcadia, Gallifrey's second city. The Eighth Doctor at first was a conscientious objector , instead working to help where he could. His attempt to save

4350-435: The best suited to the description of our world". Even as late as 1909, Poincaré continued to describe the dynamical interpretation of the Lorentz transform. In 1905, Albert Einstein analyzed special relativity in terms of kinematics (the study of moving bodies without reference to forces) rather than dynamics. His results were mathematically equivalent to those of Lorentz and Poincaré. He obtained them by recognizing that

4437-539: The character during the Time War. Space-time Until the turn of the 20th century, the assumption had been that the three-dimensional geometry of the universe (its description in terms of locations, shapes, distances, and directions) was distinct from time (the measurement of when events occur within the universe). However, space and time took on new meanings with the Lorentz transformation and special theory of relativity . In 1908, Hermann Minkowski presented

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4524-526: The cracks, which erase those they consume from history, are a result of the Silence causing the Doctor's TARDIS to explode on 26 June 2010. During the events of " The Time of the Doctor ", the Doctor discovers one remaining crack on the planet Trenzalore, through which the Time Lords transmit the First Question: "Doctor Who?". The intention is for the Doctor to give his true name, which will verify to

4611-450: The difference between what one measures and what one sees is the source of much confusion among students of relativity. By the mid-1800s, various experiments such as the observation of the Arago spot and differential measurements of the speed of light in air versus water were considered to have proven the wave nature of light as opposed to a corpuscular theory . Propagation of waves

4698-457: The distance between the two events (because of length contraction ). Special relativity provides a new invariant, called the spacetime interval , which combines distances in space and in time. All observers who measure the time and distance between any two events will end up computing the same spacetime interval. Suppose an observer measures two events as being separated in time by Δ t {\displaystyle \Delta t} and

4785-422: The entire theory can be built upon two postulates: the principle of relativity and the principle of the constancy of light speed. His work was filled with vivid imagery involving the exchange of light signals between clocks in motion, careful measurements of the lengths of moving rods, and other such examples. Einstein in 1905 superseded previous attempts of an electromagnetic mass –energy relation by introducing

4872-603: The events in series 5 and 6 and leading to the Doctor's arrival on Trenzalore. In the end, the Time Lords remain in exile and close the remaining crack, but not before granting the Doctor, old and weary from his years protecting Trenzalore, a new cycle of regenerations, which allow him to destroy the Dalek fleet surrounding the planet. In the 2006 episode " Rise of the Cybermen " when the Tenth Doctor , Rose Tyler and Mickey Smith are trapped in an alternate reality,

4959-615: The fact that spacetime is a manifold, implies that at ordinary, non-relativistic speeds and at ordinary, human-scale distances, there is little that humans might observe that is noticeably different from what they might observe if the world were Euclidean. It was only with the advent of sensitive scientific measurements in the mid-1800s, such as the Fizeau experiment and the Michelson–Morley experiment , that puzzling discrepancies began to be noted between observation versus predictions based on

5046-464: The first thirteen incarnations of the Doctor, to gather to save Gallifrey by freezing it in time and removing it from the universe. The sudden disappearance of Gallifrey left the Daleks firing upon and subsequently annihilating themselves, while the Time Lords remained; albeit powerless and forgotten. As the War Doctor regenerates into the Ninth Doctor , his memory of saving Gallifrey is wiped as

5133-556: The further development of general relativity, Einstein fully incorporated the spacetime formalism. When Einstein published in 1905, another of his competitors, his former mathematics professor Hermann Minkowski , had also arrived at most of the basic elements of special relativity. Max Born recounted a meeting he had made with Minkowski, seeking to be Minkowski's student/collaborator: I went to Cologne, met Minkowski and heard his celebrated lecture 'Space and Time' delivered on 2 September 1908. [...] He told me later that it came to him as

5220-497: The general equivalence of mass and energy , which was instrumental for his subsequent formulation of the equivalence principle in 1907, which declares the equivalence of inertial and gravitational mass. By using the mass–energy equivalence, Einstein showed that the gravitational mass of a body is proportional to its energy content, which was one of the early results in developing general relativity . While it would appear that he did not at first think geometrically about spacetime, in

5307-408: The geometric interpretation of relativity proved to be vital. In 1916, Einstein fully acknowledged his indebtedness to Minkowski, whose interpretation greatly facilitated the transition to general relativity. Since there are other types of spacetime, such as the curved spacetime of general relativity, the spacetime of special relativity is today known as Minkowski spacetime. In three dimensions,

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5394-418: The hypothetical aether on the speed of light, and the most likely explanation, complete aether dragging, was in conflict with the observation of stellar aberration . George Francis FitzGerald in 1889, and Hendrik Lorentz in 1892, independently proposed that material bodies traveling through the fixed aether were physically affected by their passage, contracting in the direction of motion by an amount that

5481-419: The implicit assumption of Euclidean space. In special relativity, an observer will, in most cases, mean a frame of reference from which a set of objects or events is being measured. This usage differs significantly from the ordinary English meaning of the term. Reference frames are inherently nonlocal constructs, and according to this usage of the term, it does not make sense to speak of an observer as having

5568-400: The link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Time_Wars&oldid=1184521743 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Time War (Doctor Who) The Time War , also called

5655-438: The math with no loss of generality in the conclusions that are reached. In Fig. 2-2, two Galilean reference frames (i.e. conventional 3-space frames) are displayed in relative motion. Frame S belongs to a first observer O, and frame S′ (pronounced "S prime") belongs to a second observer O′. Fig. 2-3a redraws Fig. 2-2 in a different orientation. Fig. 2-3b illustrates a relativistic spacetime diagram from

5742-517: The observed rate at which time passes for an object depends on the object's velocity relative to the observer. General relativity provides an explanation of how gravitational fields can slow the passage of time for an object as seen by an observer outside the field. In ordinary space, a position is specified by three numbers, known as dimensions . In the Cartesian coordinate system , these are often called x , y and z . A point in spacetime

5829-549: The past in an attempt to avert the Daleks' creation, to affect their development to make them less aggressive, or discover an inherent weakness they could exploit. In retaliation for this ultimately unsuccessful mission, the Daleks attempt to infiltrate the High Council of the Time Lords with duplicates of the Fifth Doctor in Resurrection of the Daleks (1984), followed by an open declaration of hostilities by one of

5916-471: The physical constituents of matter. Lorentz's equations predicted a quantity that he called local time , with which he could explain the aberration of light , the Fizeau experiment and other phenomena. Henri Poincaré was the first to combine space and time into spacetime. He argued in 1898 that the simultaneity of two events is a matter of convention. In 1900, he recognized that Lorentz's "local time"

6003-486: The postulate of relativity. While discussing various hypotheses on Lorentz invariant gravitation, he introduced the innovative concept of a 4-dimensional spacetime by defining various four vectors , namely four-position , four-velocity , and four-force . He did not pursue the 4-dimensional formalism in subsequent papers, however, stating that this line of research seemed to "entail great pain for limited profit", ultimately concluding "that three-dimensional language seems

6090-547: The resurrection of the Master in preparation for the war. Written by George Mann , this novel features the War Doctor and is set in the Time War. During the novel, the War Doctor and his new companion Cinder discover that the Daleks intend to use the temporal anomalies of a rift in time in the Moldox system, to develop a weapon that could completely erase Gallifrey and the Time Lords from history, with Rassilon's plan to stop

6177-513: The return of the Valeyard , who is recruited by the Time Lords attempt to be a soldier in the War after he is 'recreated' through an accident when the Doctor uses a transmat while carrying a device that can manipulate biology. The War Master series was released in December 2017. The release features Derek Jacobi reprising his role as The Master from the 2007 episode " Utopia " and follows

6264-452: The show's 50th anniversary special. Over the course of several episodes, the conflict is only implied by short clues and comments, particularly the discussion in the 2007 episode " The Sound of Drums ", and part two of the 2010 episode " The End of Time ". The Time War is finally depicted in the 50th anniversary special " The Day of the Doctor ", featuring the climax of the final battle and the Time Lords' fate. The Last Great Time War pitted

6351-733: The spacetime interval d s ′ {\displaystyle ds'} can be written in a same form as above. Because of the constancy of speed of light, the light events in all inertial frames belong to zero interval, d s = d s ′ = 0 {\displaystyle ds=ds'=0} . For any other infinitesimal event where d s ≠ 0 {\displaystyle ds\neq 0} , one can prove that d s 2 = d s ′ 2 {\displaystyle ds^{2}=ds'^{2}} which in turn upon integration leads to s = s ′ {\displaystyle s=s'} . The invariance of

6438-584: The spacetime interval between the same events for all inertial frames of reference is one of the fundamental results of special theory of relativity. Although for brevity, one frequently sees interval expressions expressed without deltas, including in most of the following discussion, it should be understood that in general, x {\displaystyle x} means Δ x {\displaystyle \Delta {x}} , etc. We are always concerned with differences of spatial or temporal coordinate values belonging to two events, and since there

6525-416: The spacetime interval between two events on the world line of something moving at the speed of light is zero. Such an interval is termed lightlike or null . A photon arriving in our eye from a distant star will not have aged, despite having (from our perspective) spent years in its passage. A spacetime diagram is typically drawn with only a single space and a single time coordinate. Fig. 2-1 presents

6612-436: The speed of light, their world lines have a slope of ±1. In other words, every meter that a photon travels to the left or right requires approximately 3.3 nanoseconds of time. To gain insight in how spacetime coordinates measured by observers in different reference frames compare with each other, it is useful to work with a simplified setup with frames in a standard configuration. With care, this allows simplification of

6699-402: The state of electrodynamics after Michelson's disruptive experiments at least since the summer of 1905, when Minkowski and David Hilbert led an advanced seminar attended by notable physicists of the time to study the papers of Lorentz, Poincaré et al. Minkowski saw Einstein's work as an extension of Lorentz's, and was most directly influenced by Poincaré. On 5 November 1907 (a little more than

6786-447: The viewpoint of observer O. Since S and S′ are in standard configuration, their origins coincide at times t  = 0 in frame S and t ′ = 0 in frame S′. The ct ′ axis passes through the events in frame S′ which have x ′ = 0. But the points with x ′ = 0 are moving in the x -direction of frame S with velocity v , so that they are not coincident with the ct axis at any time other than zero. Therefore,

6873-465: The war. Steven Moffat , writer and later executive producer for Doctor Who , has gone further, arguing that "a television series which embraces both the ideas of parallel universes and the concept of changing time can't have a continuity error—it's impossible for Doctor Who to get it wrong, because we can just say 'he changed time—it's a time ripple from the Time War ' ". The Last Great Time War also features in various Doctor Who spin-off media. In

6960-483: The war. Ultimately, Rassilon , founder of the Time Lord society and its time travel technology, is resurrected to assume leadership as Lord President. Refusing the possibility of his civilisation being destroyed by the Daleks, Rassilon prepares a doomsday scenario. It included sacrificing all of time itself, thereby destroying the Daleks and all life in the universe. The Time Lords themselves would have transcended into

7047-406: The whole ensemble of clocks associated with one inertial frame of reference. In this idealized case, every point in space has a clock associated with it, and thus the clocks register each event instantly, with no time delay between an event and its recording. A real observer, will see a delay between the emission of a signal and its detection due to the speed of light. To synchronize the clocks, in

7134-545: Was "usually happy for old and new fans to invent the Complete History of the Doctor in their heads, completely free of the production team's hot and heavy hands". The sixth series of Gallifrey features the Daleks invading Gallifrey, but this invasion is undone thanks to Lord President Romana, Leela, K9 and Narvin, aided by Romana's future self. The ninth series more directly featured the Time War with Romana and Leela playing key roles, including Leela being sent on

7221-555: Was exactly what was necessary to explain the negative results of the Michelson–Morley experiment. No length changes occur in directions transverse to the direction of motion. By 1904, Lorentz had expanded his theory such that he had arrived at equations formally identical with those that Einstein was to derive later, i.e. the Lorentz transformation . As a theory of dynamics (the study of forces and torques and their effect on motion), his theory assumed actual physical deformations of

7308-536: Was less than the sum of the speed of light in air plus the speed of the water by an amount dependent on the water's index of refraction. Among other issues, the dependence of the partial aether-dragging implied by this experiment on the index of refraction (which is dependent on wavelength) led to the unpalatable conclusion that aether simultaneously flows at different speeds for different colors of light. The Michelson–Morley experiment of 1887 (Fig. 1-2) showed no differential influence of Earth's motions through

7395-500: Was no need for a Doctor in a universe consumed by war, and regenerates into the War Doctor . Davros , the creator of the Daleks, also fights during the war after his creations rehabilitated him to a leadership position. In the first year of the War, Davros' command ship is seemingly destroyed. Unbeknownst to the Doctor, who had tried to save him, Davros is rescued by Dalek Caan , via an emergency temporal shift. The war results in countless millions dying endless deaths, as time travel

7482-490: Was produced by Big Finish Productions following John Hurt 's role as the War Doctor in “ The Day of the Doctor ”. Hurt reprised his role alongside Jacqueline Pearce as Cardinal Ollistra, who frequently sends the War Doctor on missions to give the Time Lords the upper hand over the Daleks . Following Hurt's death, the series ended after four volumes in February 2017. A follow-up series was subsequently launched featuring

7569-414: Was then assumed to require the existence of a waving medium; in the case of light waves, this was considered to be a hypothetical luminiferous aether . The various attempts to establish the properties of this hypothetical medium yielded contradictory results. For example, the Fizeau experiment of 1851, conducted by French physicist Hippolyte Fizeau , demonstrated that the speed of light in flowing water

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